Garden Tips: Repotting orchids is easier than you think

Today, you can go into almost any store that sells houseplants and find blooming orchids available at reasonable prices. Orchids are no longer exotic plants grown only in the tropics or by experts with greenhouses. You and I can grow them fairly easily in our homes, but the care does differ from that of other houseplants.

Most of the approximately 28,000 species of orchids are epiphytes. Epiphytes are plants that grow upon other plants but do not obtain water or nutrients from those plants. In their natural habitat, epiphytic orchids typically grow on tree trunks and branches. They hang onto their hosts with thick aerial roots and use those roots to absorb water and nutrients found on the surface of the bark. In addition, these thick roots store water and are capable of photosynthesis.

Orchids cannot be grown in the typical potting media used for houseplants.

The roots of epiphytic orchids are covered with a protective spongy layer of dead tissue called velamen. The velamen plays an important role in the absorption of water and nutrients by these aerial roots and it also protects the roots from UV-B radiation. If you remove an epiphytic orchid from its pot, the velamen on the roots will be white when the roots are dry, and transparent when moist and full of water.

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Because the roots of epiphytic orchids are not typical houseplant roots, orchids cannot be grown in the typical potting media used for houseplants. They require special orchid media that provides conditions similar to those found on the bark of a tree. The media must furnish generous aeration, allow for good drainage and retain some moisture. There are commercial orchid mixes available containing coarse fir bark and perlite, but orchid experts often create their own mix using materials that meet the specific needs of their orchids.

Experts also use special orchid pots that provide plenty of aeration to the roots. These plastic or clay pots have slots on the sides for aeration in addition to holes in the bottoms for drainage.

Epiphytic orchids typically grow on tree trunks and branches.

Orchids that die at the hands of their owners usually fail either because they were watered incorrectly or they were not repotted when necessary. Orchid roots must have moisture and air. Orchids should be watered whenever the potting mix starts to dry out. When watered, good drainage is essential because orchid roots should not be allowed to sit in water.

Orchid media gradually breaks down and deteriorates, no longer providing the needed aeration. Because of this, orchid experts recommend repotting orchids every two to three years. I was afraid to take on the task of repotting, so my orchids were languishing on my windowsill and appeared to be dying. I had to do something, so two months ago I mustered the courage to repot them.

Repotting was easier than I imagined. Working over a plastic wash tub, I carefully removed each plant from its pot and gently removed all the old growing media from the roots. Using clean pruning snips, I cut off any obviously dead, shriveled or mushy roots. I also sterilized the snips between cuts to prevent spreading disease.

Orchids are epiphytes, which are plants that grow upon other plants but do not obtain water or nutrients from those plants.

I then repotted each plant by wrapping the roots around so they would fit into the clean, somewhat larger orchid pot I had ready for it. I first placed some orchid media in the bottom of the pot and then situated the plant in the pot so that the crown at the base of the leaves was about a half-inch from the top of the pot. Once in the pot, I packed fresh dampened orchid media around the roots, using a chopstick to gently push the media into any voids between the roots. I finished by watering the plants to help settle the media around the roots. Now my orchids are looking much better.

Marianne C. Ophardt is a horticulturist for Washington State University Benton County Extension.

Orchid show planned Oct. 1-2 in Kennewick

An orchid sale and show is planned Oct. 1-2 at the Tri-Tech Skills Center, 5929 W. Metaline Ave., Kennewick.

Orchid club members will be on hand to answer questions, and attendees can buy plants and supplies. Seminars on various orchid types are also planned.

Admission is $3. Hours are from 11 a.m. to 5 p.m. Oct. 1 and from 10 a.m. to 3 p.m. Oct. 2.